Alpha adrenergic activity and renal function in two‐kidney deoxycorticosterone‐acetate hypertensive swine

Abstract

AbstractTo evaluate the role of alpha‐adrenergic activity in deoxycorticosterone‐acetate (DOCA) hypertensive swine, eight two‐kidney Yucatan miniature swine were implanted with DOCA silicone strips (100 mg/kg) for 12–16 weeks. Mean arterial pressure (MAP) in these animals increased progressively from control values of approximately 1 15 mm Hg to 173 ± 5 mm Hg. Treatment of four conscious animals with phenoxybenzamine (POB) (1 mg/kg) resulted in a significant decrease in MAP from 190 ± 3 to 157 ± 5 mm Hg (P < 0.05). This decline was due to a 21% decrease in total peripheral resistance (TPR) (P < 0.05), while cardiac output (CO) and heart rate (HR) remained unchanged. Pentobarbital anesthesia caused a small insignificant decrease in MAP to 165 ± 5 mm Hg. While under anesthesia, infusion of POB into the left renal artery (0.04 μg/kg/min) caused a slight increase in left renal blood flow (P > 0.05), without affecting MAP, HR, TPR, or CO. Left kidney urine flow and sodium excretion also increased during intra‐renal POB infusion. Potassium excretion was unchanged and GFR decreased slightly. When POB (1 mg/kg) was infused systemically during anesthesia, MAP decreased to 82 ± 6 mmHg (P < 0.05). This was due to a 34% and 14% decrease in TPR and CO, respectively (P < 0.05). Whole animal urine flow, sodium excretion, and GFR all decreased significantly with systemic POB. These findings suggest that alpha‐adrenergic activity plays a role in the maintenance MAP and the determination of renal function in DOCA hypertensive swine.